Technical Abstract:
Aflatoxins are highly toxic and hepatocarcinogenic compounds produced by Aspergillus flavus and A. parasiticus during infection of corn (maize), peanuts, cotton seed, and tree nuts (Figure 1). To minimize exposure to aflatoxins the U.S. Food and Drug Administration enforces a 20 ppb limit of aflatoxin content in foodstuffs. Aflatoxin contamination becomes increasingly problematic when corn is used as a feedstock for ethanol production. Although aflatoxin has not been reported in ethanol produced from contaminated products, the distiller’s grains produced during fermentation show a marked increase in aflatoxin levels, typically 3-4 times the initial value. Distiller’s grains are key components in many animal feeds and generate a large portion of revenue for distilleries. Though ethanol plants can utilize aflatoxin-contaminated corn to generate ethanol, the FDA limitations prevent utilizing the distiller’s grains as animal feed products thus making the whole process uneconomic. Several chemical methods have been shown to be effective in removing aflatoxin; however, they are not approved by the FDA and are too expensive to be feasible on an industrial level. Thus, we are in the initial stages of characterizing aflatoxin degradation by both toxic and nontoxic Aspergillus species. The degradation of exogenously introduced aflatoxin has been confirmed by Thin Layer Chromatography (TLC) and LC-MS/MS and will serve as the basis for identification of genes and enzymes involved in this unique phenomenon. Identifying the factors responsible for this process will allow for the removal of aflatoxins from contaminated substrates by co-inoculation or expression of these factors in either cell free extracts and/or modified yeast for use in kernel and cob ethanol production; therefore, increasing the economic feasibility of ethanol as an alternative fuel as well as providing an additional market for a previously unutilized resource.